/Engine/Source/Runtime/Engine/Classes/Engine/Polys.h
Breaks down this polygon into triangles. The triangles are then returned to the caller in an array.
The number of triangles created
int32 Triangulate ( [ABrush](API\Runtime\Engine\Engine\ABrush) * InOwnerBrush, [TArray](API\Runtime\Core\Containers\TArray)< [FPoly](API\Runtime\Engine\Engine\FPoly) > & OutTriangles )